For people who follow the stock market, how reliable an indicator of what the markets are likely to do next is the Shiller PE, which is the ratio of price to earnings,
Here's why Robert Shiller's two stock-market indexes are telling wildly different valuation stories. - MarketWatch
![Historical Shiller PE of the Brazilian stock market and the IPOs of the... | Download Scientific Diagram Historical Shiller PE of the Brazilian stock market and the IPOs of the... | Download Scientific Diagram](https://www.researchgate.net/publication/321924041/figure/fig2/AS:573440933326848@1513730380151/Historical-Shiller-PE-of-the-Brazilian-stock-market-and-the-IPOs-of-the-EBX-Groups.png)